Drill unit



Feb. 20, 1951 GROSSMAN 2,542,866

DRILL UNIT Filed May 3, 1950 INVENTOR fiEW/A/ 5. 6205s Mfi V ATTORN EY Patented Feb. 20, 1951 UNITED STATES PATENT OFFICE 3Claims. l

This invention is a pneumatically operable drill unit designed for high speed drilling with its air cylinder forming an integral part of the unit. One object of the invention is to provide a unit of small dimensions and compact construction to permit a plurality of these units, when mounted in gang, to position the drill tools relatively close to one another for multiple drilling.

A further object of the invention is to provide a drill unit of great simplicity and one which may be economically manufactured and sold at a relatively low price.

In the unit of this invention, the drill bit is supported in a chuck mounted upon a rotatable spindle embraced by a tubular piston stem on which the pneumatic piston is rigidly supported, the spindle and piston stem being axially movable as a unit and the spindle rotatable with respect to the stem. The stem is supported at its opposite ends in bearing blocks which extend to one side of the unit and are there rigidly tied to one another by a stop rod arranged parallel to the stem and adapted to reciprocate therewith. This rod passes through a bearing in the body of the unit in which the cylinder is formed and said bearing is of such length as to maintain the stem and rod at all times in parallel relation. This support of the piston stem eliminates bending stresses on the stem and spindle and assures more accurate boring, as will hereinafter be more fully explained. The stop rod serves the additional purpose of limiting the throw of the piston' in both directions to a predetermined zone of operation and thus controls the depth of the drilled holes as illustrative, only, and not as defining the 2 v body'of the unit. It is of elongated form and o the cross section shown in Figure 3. Its structure is such that it maybe either cast or extruded for economy in production. In one side of the body is formed a cylinder [the opposite ends of which are internally threaded, as at'3. Extending parallel of the cylinder, but at the opposite side of the body is a circular hole 4 which extends through the entire height of the body. This hole serves as a guide bearing for a stop rod 5'hereinafter described. y

The upper and lower ends of the cylinder are closed by end caps 6 and 1, these caps having reduced threaded portions adapted to screw into the threads 3 of the cylinder to rigidly mount the caps at the opposite ends of'said cylinder. Each of these end caps 6 and l is bored and counter-bored to provide an inwardly facing shoulder 8 and within each cap is positioned a sleeve 9. The inner end of each sleeve has an external flange Iii adapted to be tightly seated against the corresponding shoulder 8 of the end caps by a sleeve nut ll, threaded o to the exterior of the sleeve and bearing against the outer face of the cap to rigidly support the sleeve 9 upon the cap.

Operable within the cylinder 2 is a piston l2. This piston is afiixed to a tubular piston step I3 which extends upwardly through the upper sleeve 9 and downwardly through the corresponding lower sleeve with close sliding fit. Suitable packings M with packing nuts 15 preclude leakage between the piston stem and the sleeves 9.

The piston may be either single or double acting but, for the purpose of illustration, 1 have shown it double acting. When so made, it may conveniently comprise a pair of opposed cup washers l6 positioned back to back against an interposed disk and held in place by spring retainers l7, seated in circular grooves in the piston stem above and below external disks IS. The upper and lower ends of the piston stem !3 are reduced beyond shoulders l9 and said reduced ends extend into openings in upper and lower bearing blocks 22 and 2 i, respectively. In each of such openings, beyond the ends of the piston stem, are positioned anti-friction bearings 22, shown as ball bearings. The outer races or" these bearings are supported in the blocks 26 and 2|, while the inner races embrace the spindle 23. Spring retainers 24 seat in grooves in the spindle externally of the anti-friction bearings and serve to retain the bearing blocks on the pisto stern and lock the stem and spindle against relative i the upper end of the spindle is secured a pulley 25 by which the spindle is belt rotated from any suitable prime mover. The pulley is shown with its hub supported for rotation i an anti-friction bearing; 25 mounted in the uppeiyportioniof a cage-like extension '21, the lowenend of which embraces the upper sleeve nut I and is secured thereto by a force fit, set screws, or in any other suitable manner.

When thus mounted, the pulley must be slidably mounted on the spindle. vslidingrcon-1' nection may be in the form of anordinary bar 'key and slot connection. Howeven'I prefer to form a slot in the shaft, a registering slot 'i-nthe pulley hub, and utilize :as the key, one or more steel balls 2'! .(similar .to ball bearings) .held in placein the hub, ofthepulley'by .a retainingscrew 28, as shown in.. Figure 2. Such a key serves to effiectuallydock the pulley and spindle against relative rotation while permitting .freer sliding movement 'thanwould result from the. use of the .usual' bar key. While the extensionll and its. use tosupport thepulleyas shown is preferred, this extension. is not essential. .It may be omitted, 'in-whichcase the pulley might well be rigidly secured to the spindle in any suita'blemahner' as the .axialmovement of the spindle would ordinarilybe taken up bythe drive belt.

- As best .showndn Figured, the upper .and lower bearing blocks 20 and 2|, which support the oppositeends of the piston stem, extend'radially from said stem .and are rigidly secured to one another .by a combined brace and stop rod 5. 'The. connection between'therod'5 and these hearing blocksi a rigidand immovableiconnection, so zasto .firmly tie'together the. pistonstem and the rod 5 as clearly shown in Figure 4. .Thejrod SeXtends vertically through the bearing! of 'a length even, greater than the effective length of the cylinder '2. The rod l. is made ofsufficient cross section to resist twisting or bending strains and, inasmuch a it .extends through the "long bearing 4,.it serves to positivelysupport'thebearings at the opposite ends of the piston stem in such'manner as to eliminate all bendingistresses on. saidstem. Moreover, thisirod and th fbear ing blocks 20 and '21 move with the stem and thus support and guide it at all'times. 'Thisfact, together with the further fact that'the stem extends through the sleeves 8 between the bearing blocks, assures 'absolute'alinement of the sleeve at all times and eliminates bindingof theispindle within the sleeve. These facts -are important, particularly in conjunction with the further "fact that the piston stem and'spindle axially move withjone another and are :tied itogetheragainst .relative axial movement. There is'thus "practi'cally no iwear between any jpartpfithesleeve and spindle and 'the'spindle "is'thus caused -to runtrue and without whip or radial 'lost "motion. Consequently the .drill bit 'willdrill 'accurately for unlimited periods. The rod '5'is threaded andprovidedabove and below'the body with adjusting-nuts 29 and lock'nuts 30 to'control thethrow ofthepiston in'both directions.

As hereinbefore stated, the pistonis shown as.

double actingand 'it'is adapted tobe. pneumatically'operated in both 'directions'by compressed air admitted through tapped holes 3 1 ,formed in the end caps B'and "I of the cylinder. Anumber of these tapped holes areprovided in 'each cap and any one of such holes in each cap may be utilized,

as may be most convenient to the air supply.

Those utilized are fitted with hose connecting nipples 32, as shown in Figure 2, while the others are sealed by threaded plugs 33. Ducts 34 lead from each of the tapped holes 3| to the interior of the corresponding end of the cylinder Air under pressure is thus admitted into the opposite ends "of ='thez'-cylind'er,fwith the admission-=and release controlled' by appropriate--airvalves "associated with the compressed air supply system and form- Liing no part of the present invention.

While the piston has been shown as double acting, it may be made single acting in a down- Ward-zdirectionrari'd a spring 35 may be utilized to elevate the pistonduring the retractive movement ""of' th'e drill bit. In fact the spring may be used even with a double acting piston to speed up the retraction of the drill bit. If a single acting piston. -is.employed,- one .or more of ethe tapped holes-T35 in the :lower .cap shouldbeileftropen.

' It will .be apparentlfrom the foregoing .detailed description, .that the structure ,of this .unitQis extremelysimple. "The partsrequire -.very. little machining .and .standard bearings may .be used. Thebody otthetool maybe extruded, asstated, and standard parts may be .used for many parts of .the structure. Consequently thi .unit .can be very cheaply manufactured-and sold at .a much lower price than is ordinarily the .case forunits .of this general character.

Furthermore, the parts areso compactlthatthe overall cross sectional dimensions maybe made extremely smallandyet the unit will .function withhigh efliciency. With suchsmallcrosssectional dimensions, a number .of these toolsma-y be mounted, .by means ofany desired .brackets, stands or other means,-with the drill bits very close .to one anothenso .thata number .of holes may be drilled simultaneously. in ver close proximitytoone another. This is in .markedcontradistinction to the usualpriorpractice where it.isfr'equently necessary to shift the work between .drilling operations on' holes in close -proxin'i'ity.

- The'foregoing detailed description s'etslforth the invention in its preferred practical form,"but the invention is 'to'be understood as 'ililly commensurate with the appended claims.

Having thus fully described the invention, what .I claim as new and desire to secure "by LettersiPatent is:

' 1. A drill unit comprising: an elongated body provided longitudinally thereof with a.c'ylinder chamber anda combined brace and stop rod bearing laterally of said 'cha'mber' and extending parallel thereto, cylinder caps at the oppiosite ends of said'cylinder, apiston in said cylinder having a tubular piston stem coaxial, 0'1

and extendingfrom both sides of the piston through .both cylinder caps, bearing blocks.

-to the'brace and stop rod, 'stop nuts'thre'aded on to the stop'rodbeyond the opposite ends of said body to limit the throw of the piston on both directions, a spindle extending through and coaxially with the tubularpiston stemand mounted in bearings carried by the bearing blocks, means "for securing the spindle :against axial movementrelative to 'thefpiston stem/the rigid connection between "the "brace and "stop rod, the blocks, and the stem functioning to retain the stem in true alignment whereby to eliminate binding of the spindle within the stern, means for rotating the spindle, and means for introducing compressed air into the cylinder to operate the piston to axially reciprocate the stem and brace and stop rod as a unit. 2. A drill unit comprising: an elongated body with a cylinder chamber and a guide bearing extending in parallel spaced apart relation from one end to the other end of said body, a piston in the cylinder chamber, said piston having a tubular stem slidably mounted within and extending beyond both ends of said cylinder chamber, a spindle rotatably passing through the tubular stem and locked against axial movement relative thereto, blocks mounted on the opposite ends of said stem and extending laterally therefrom, a brace rod slidably mounted in and extending through the guide bearing with its opposite ends rigidly and immovably connected to said blocks to rigidly secure the piston stem to the brace rod, whereby to retain the stem in true alignment and eliminate binding of the spindle within the stem, means to rotate the spindle, and means to axially reciprocate the piston, stem and brace rod as a unit.

3. A drill unit comprising: an elongated body with a chamber and a guide bearing extending in parallel spaced apart relation from one end retain the stem in true alignment and eliminate binding of the spindle within the stem, means to rotate the spindle, and means to axially reciprocate the stem and brace rod as a unit.

DARWIN B. GROSSMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,434,564 Ruetschi Nov. '7, 1922 2,446,393 Russell Aug. 3, 1948 FOREIGN PATENTS Number Country Date 198,473 Great Britain June 7, 1923 

